/usr/include/boost/random/uniform_int_distribution.hpp is in libboost1.49-dev 1.49.0-3.2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 | /* boost random/uniform_int_distribution.hpp header file
*
* Copyright Jens Maurer 2000-2001
* Copyright Steven Watanabe 2011
* Distributed under the Boost Software License, Version 1.0. (See
* accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*
* See http://www.boost.org for most recent version including documentation.
*
* $Id: uniform_int_distribution.hpp 71018 2011-04-05 21:27:52Z steven_watanabe $
*
* Revision history
* 2001-04-08 added min<max assertion (N. Becker)
* 2001-02-18 moved to individual header files
*/
#ifndef BOOST_RANDOM_UNIFORM_INT_DISTRIBUTION_HPP
#define BOOST_RANDOM_UNIFORM_INT_DISTRIBUTION_HPP
#include <iosfwd>
#include <ios>
#include <istream>
#include <boost/config.hpp>
#include <boost/limits.hpp>
#include <boost/assert.hpp>
#include <boost/random/detail/config.hpp>
#include <boost/random/detail/operators.hpp>
#include <boost/random/detail/uniform_int_float.hpp>
#include <boost/random/detail/signed_unsigned_tools.hpp>
#include <boost/type_traits/make_unsigned.hpp>
#include <boost/type_traits/is_integral.hpp>
namespace boost {
namespace random {
namespace detail {
#ifdef BOOST_MSVC
#pragma warning(push)
// disable division by zero warning, since we can't
// actually divide by zero.
#pragma warning(disable:4723)
#endif
template<class Engine, class T>
T generate_uniform_int(
Engine& eng, T min_value, T max_value,
boost::mpl::true_ /** is_integral<Engine::result_type> */)
{
typedef T result_type;
typedef typename make_unsigned<T>::type range_type;
typedef typename Engine::result_type base_result;
// ranges are always unsigned
typedef typename make_unsigned<base_result>::type base_unsigned;
const range_type range = random::detail::subtract<result_type>()(max_value, min_value);
const base_result bmin = (eng.min)();
const base_unsigned brange =
random::detail::subtract<base_result>()((eng.max)(), (eng.min)());
if(range == 0) {
return min_value;
} else if(brange == range) {
// this will probably never happen in real life
// basically nothing to do; just take care we don't overflow / underflow
base_unsigned v = random::detail::subtract<base_result>()(eng(), bmin);
return random::detail::add<base_unsigned, result_type>()(v, min_value);
} else if(brange < range) {
// use rejection method to handle things like 0..3 --> 0..4
for(;;) {
// concatenate several invocations of the base RNG
// take extra care to avoid overflows
// limit == floor((range+1)/(brange+1))
// Therefore limit*(brange+1) <= range+1
range_type limit;
if(range == (std::numeric_limits<range_type>::max)()) {
limit = range/(range_type(brange)+1);
if(range % (range_type(brange)+1) == range_type(brange))
++limit;
} else {
limit = (range+1)/(range_type(brange)+1);
}
// We consider "result" as expressed to base (brange+1):
// For every power of (brange+1), we determine a random factor
range_type result = range_type(0);
range_type mult = range_type(1);
// loop invariants:
// result < mult
// mult <= range
while(mult <= limit) {
// Postcondition: result <= range, thus no overflow
//
// limit*(brange+1)<=range+1 def. of limit (1)
// eng()-bmin<=brange eng() post. (2)
// and mult<=limit. loop condition (3)
// Therefore mult*(eng()-bmin+1)<=range+1 by (1),(2),(3) (4)
// Therefore mult*(eng()-bmin)+mult<=range+1 rearranging (4) (5)
// result<mult loop invariant (6)
// Therefore result+mult*(eng()-bmin)<range+1 by (5), (6) (7)
//
// Postcondition: result < mult*(brange+1)
//
// result<mult loop invariant (1)
// eng()-bmin<=brange eng() post. (2)
// Therefore result+mult*(eng()-bmin) <
// mult+mult*(eng()-bmin) by (1) (3)
// Therefore result+(eng()-bmin)*mult <
// mult+mult*brange by (2), (3) (4)
// Therefore result+(eng()-bmin)*mult <
// mult*(brange+1) by (4)
result += static_cast<range_type>(random::detail::subtract<base_result>()(eng(), bmin) * mult);
// equivalent to (mult * (brange+1)) == range+1, but avoids overflow.
if(mult * range_type(brange) == range - mult + 1) {
// The destination range is an integer power of
// the generator's range.
return(result);
}
// Postcondition: mult <= range
//
// limit*(brange+1)<=range+1 def. of limit (1)
// mult<=limit loop condition (2)
// Therefore mult*(brange+1)<=range+1 by (1), (2) (3)
// mult*(brange+1)!=range+1 preceding if (4)
// Therefore mult*(brange+1)<range+1 by (3), (4) (5)
//
// Postcondition: result < mult
//
// See the second postcondition on the change to result.
mult *= range_type(brange)+range_type(1);
}
// loop postcondition: range/mult < brange+1
//
// mult > limit loop condition (1)
// Suppose range/mult >= brange+1 Assumption (2)
// range >= mult*(brange+1) by (2) (3)
// range+1 > mult*(brange+1) by (3) (4)
// range+1 > (limit+1)*(brange+1) by (1), (4) (5)
// (range+1)/(brange+1) > limit+1 by (5) (6)
// limit < floor((range+1)/(brange+1)) by (6) (7)
// limit==floor((range+1)/(brange+1)) def. of limit (8)
// not (2) reductio (9)
//
// loop postcondition: (range/mult)*mult+(mult-1) >= range
//
// (range/mult)*mult + range%mult == range identity (1)
// range%mult < mult def. of % (2)
// (range/mult)*mult+mult > range by (1), (2) (3)
// (range/mult)*mult+(mult-1) >= range by (3) (4)
//
// Note that the maximum value of result at this point is (mult-1),
// so after this final step, we generate numbers that can be
// at least as large as range. We have to really careful to avoid
// overflow in this final addition and in the rejection. Anything
// that overflows is larger than range and can thus be rejected.
// range/mult < brange+1 -> no endless loop
range_type result_increment =
generate_uniform_int(
eng,
static_cast<range_type>(0),
static_cast<range_type>(range/mult),
boost::mpl::true_());
if((std::numeric_limits<range_type>::max)() / mult < result_increment) {
// The multiplcation would overflow. Reject immediately.
continue;
}
result_increment *= mult;
// unsigned integers are guaranteed to wrap on overflow.
result += result_increment;
if(result < result_increment) {
// The addition overflowed. Reject.
continue;
}
if(result > range) {
// Too big. Reject.
continue;
}
return random::detail::add<range_type, result_type>()(result, min_value);
}
} else { // brange > range
base_unsigned bucket_size;
// it's safe to add 1 to range, as long as we cast it first,
// because we know that it is less than brange. However,
// we do need to be careful not to cause overflow by adding 1
// to brange.
if(brange == (std::numeric_limits<base_unsigned>::max)()) {
bucket_size = brange / (static_cast<base_unsigned>(range)+1);
if(brange % (static_cast<base_unsigned>(range)+1) == static_cast<base_unsigned>(range)) {
++bucket_size;
}
} else {
bucket_size = (brange+1) / (static_cast<base_unsigned>(range)+1);
}
for(;;) {
base_unsigned result =
random::detail::subtract<base_result>()(eng(), bmin);
result /= bucket_size;
// result and range are non-negative, and result is possibly larger
// than range, so the cast is safe
if(result <= static_cast<base_unsigned>(range))
return random::detail::add<base_unsigned, result_type>()(result, min_value);
}
}
}
#ifdef BOOST_MSVC
#pragma warning(pop)
#endif
template<class Engine, class T>
inline T generate_uniform_int(
Engine& eng, T min_value, T max_value,
boost::mpl::false_ /** is_integral<Engine::result_type> */)
{
uniform_int_float<Engine> wrapper(eng);
return generate_uniform_int(wrapper, min_value, max_value, boost::mpl::true_());
}
template<class Engine, class T>
inline T generate_uniform_int(Engine& eng, T min_value, T max_value)
{
typedef typename Engine::result_type base_result;
return generate_uniform_int(eng, min_value, max_value,
boost::is_integral<base_result>());
}
}
/**
* The class template uniform_int_distribution models a \random_distribution.
* On each invocation, it returns a random integer value uniformly
* distributed in the set of integers {min, min+1, min+2, ..., max}.
*
* The template parameter IntType shall denote an integer-like value type.
*/
template<class IntType = int>
class uniform_int_distribution
{
public:
typedef IntType input_type;
typedef IntType result_type;
class param_type
{
public:
typedef uniform_int_distribution distribution_type;
/**
* Constructs the parameters of a uniform_int_distribution.
*
* Requires min <= max
*/
explicit param_type(
IntType min_arg = 0,
IntType max_arg = (std::numeric_limits<IntType>::max)())
: _min(min_arg), _max(max_arg)
{
BOOST_ASSERT(_min <= _max);
}
/** Returns the minimum value of the distribution. */
IntType a() const { return _min; }
/** Returns the maximum value of the distribution. */
IntType b() const { return _max; }
/** Writes the parameters to a @c std::ostream. */
BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, param_type, parm)
{
os << parm._min << " " << parm._max;
return os;
}
/** Reads the parameters from a @c std::istream. */
BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, param_type, parm)
{
IntType min_in, max_in;
if(is >> min_in >> std::ws >> max_in) {
if(min_in <= max_in) {
parm._min = min_in;
parm._max = max_in;
} else {
is.setstate(std::ios_base::failbit);
}
}
return is;
}
/** Returns true if the two sets of parameters are equal. */
BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(param_type, lhs, rhs)
{ return lhs._min == rhs._min && lhs._max == rhs._max; }
/** Returns true if the two sets of parameters are different. */
BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(param_type)
private:
IntType _min;
IntType _max;
};
/**
* Constructs a uniform_int_distribution. @c min and @c max are
* the parameters of the distribution.
*
* Requires: min <= max
*/
explicit uniform_int_distribution(
IntType min_arg = 0,
IntType max_arg = (std::numeric_limits<IntType>::max)())
: _min(min_arg), _max(max_arg)
{
BOOST_ASSERT(min_arg <= max_arg);
}
/** Constructs a uniform_int_distribution from its parameters. */
explicit uniform_int_distribution(const param_type& parm)
: _min(parm.a()), _max(parm.b()) {}
/** Returns the minimum value of the distribution */
IntType min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return _min; }
/** Returns the maximum value of the distribution */
IntType max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return _max; }
/** Returns the minimum value of the distribution */
IntType a() const { return _min; }
/** Returns the maximum value of the distribution */
IntType b() const { return _max; }
/** Returns the parameters of the distribution. */
param_type param() const { return param_type(_min, _max); }
/** Sets the parameters of the distribution. */
void param(const param_type& parm)
{
_min = parm.a();
_max = parm.b();
}
/**
* Effects: Subsequent uses of the distribution do not depend
* on values produced by any engine prior to invoking reset.
*/
void reset() { }
/** Returns an integer uniformly distributed in the range [min, max]. */
template<class Engine>
result_type operator()(Engine& eng) const
{ return detail::generate_uniform_int(eng, _min, _max); }
/**
* Returns an integer uniformly distributed in the range
* [param.a(), param.b()].
*/
template<class Engine>
result_type operator()(Engine& eng, const param_type& parm) const
{ return detail::generate_uniform_int(eng, parm.a(), parm.b()); }
/** Writes the distribution to a @c std::ostream. */
BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, uniform_int_distribution, ud)
{
os << ud.param();
return os;
}
/** Reads the distribution from a @c std::istream. */
BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, uniform_int_distribution, ud)
{
param_type parm;
if(is >> parm) {
ud.param(parm);
}
return is;
}
/**
* Returns true if the two distributions will produce identical sequences
* of values given equal generators.
*/
BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(uniform_int_distribution, lhs, rhs)
{ return lhs._min == rhs._min && lhs._max == rhs._max; }
/**
* Returns true if the two distributions may produce different sequences
* of values given equal generators.
*/
BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(uniform_int_distribution)
private:
IntType _min;
IntType _max;
};
} // namespace random
} // namespace boost
#endif // BOOST_RANDOM_UNIFORM_INT_HPP
|